A few days ago I ordered some Riptide Pivot cups for my Caliber II's. I wasn't paying attention much to the checkout and accidentally ordered two sets of them.
I swapped out the stock pivot cups and threw in the Riptides and this is what happens. Its a bit hard to see, but the trucks are slanted. When going into a carve they have ABSOLUTELY NO return to center. They just stay dead with no rebound what so ever. I thought the first set was just a dud and I tried to second set I had. SAME EXACT THING. At that point I thought it was my trucks for some reason so I asked my friend to try them on his trucks. Same exact problem. I even tried lubing them up just a little, it sorta worked for a day or two but after that back to the same thing.
I never once had a problem with Riptide Pivot cups on any of my other trucks. But I'm going to have to say that they really fucked up with Caliber II's.

@Mannith I have Cal 2 trucks and I bought Cal 2 cups. I spent almost 30 minutes last night making sure everything was aligned properly and it is. Even had a friend looked with me. It notice one set I had was for Cal 1's and I threw them on with no problems on my other Cal 1's. The set for the Cal 2's is my problem. It seems the cups are too tight to the point where the pivot has too much resistance.